Cementing material based on cooperation of low-sulfur cyanidation tailings and multi-element solid waste as well as preparation method and application of cementing material

Abstract

The invention relates to the technical field of industrial solid waste resource utilization and environmental protection treatment, and discloses a cementing material based on low-sulfur cyanidation tailings and multi-element solid waste and a preparation method and application of the cementing material. According to the invention, the multi-element solid waste is synergistically utilized, the low-sulfur cyanidation tailings are taken as a main raw material and matched with the red mud, the fly ash and the steel slag, and components such as Fe, S and SiO2 in the tailings react with active components in the multi-element solid waste to generate the high-activity sulphoaluminate cement clinker by optimizing the proportioning ratio and a roasting process, so that cyanide is synchronously decomposed to realize harmlessness, and the high-activity sulphoaluminate cement clinker is obtained. The gelling performance is further improved through gypsum excitation, and finally the gelling material with the compressive strength meeting the 42.5-grade sulphoaluminate cement standard is prepared, so that the mine filling requirement is met, and'waste is treated with waste and resources are recycled 'is realized.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization and environmental governance technology, specifically to a cementitious material based on low-sulfur cyanide tailings and synergistic multi-component solid waste, its preparation method, and its application. Background Technology

[0002] Cyanide tailings from the gold industry are included in the National Hazardous Waste List (HW33) due to their content of highly toxic cyanide, heavy metals, and residual flotation reagents. Currently, low-sulfur cyanide tailings are mainly disposed of by tailings ponds, which not only occupy a large amount of land resources but also easily pollute the soil, water, and atmosphere through leakage and dust, and tailings ponds pose safety hazards such as collapse.

[0003] Existing technologies for treating low-sulfur cyanide tailings mainly fall into two categories: harmless disposal and resource utilization. Harmless disposal technologies (such as acidification recovery and pressure filtration washing) suffer from problems such as complex processes, high energy consumption, incomplete cyanide decomposition, and the potential for secondary pollution. Resource utilization technologies primarily focus on the recovery of single elements (such as gold, silver, and iron), resulting in low recovery rates of valuable elements and insufficient overall utilization of the tailings. In terms of cementitious material preparation, existing technologies often use cyanide tailings alone to replace a portion of cement raw materials. However, due to the low cementitious activity of the tailings, a high proportion of cement clinker or a large amount of chemical activators is required, leading to insufficient product strength, high costs, and difficulty in achieving industrial application. Summary of the Invention

[0004] This invention addresses the pollution caused by the stockpiling of low-sulfur cyanide tailings and the inefficiency and high consumption of existing treatment technologies. It provides a cementitious material based on low-sulfur cyanide tailings and co-processed with multiple solid wastes, along with its preparation method and application. Through the synergistic utilization of multiple solid wastes, using low-sulfur cyanide tailings as the main raw material, combined with red mud, fly ash, and steel slag, and by optimizing the ingredient ratio and calcination process, the Fe, S, and SiO2 components in the tailings react with the active components in the multiple solid wastes to generate highly active sulfoaluminate cement clinker. Simultaneously, cyanide is decomposed to achieve harmlessness. Furthermore, gypsum activation further enhances the cementitious properties, ultimately producing a cementitious material that meets the requirements for mine backfilling, achieving "waste treatment and resource recycling."

[0005] In a first aspect, the present invention provides a cementitious material based on low-sulfur cyanide tailings and co-processed multi-component solid waste, which is prepared by mixing and grinding sulfoaluminate cement clinker and gypsum; wherein, The sulfoaluminate cement clinker is obtained by high-temperature oxidation roasting of mixed raw meal; the mixed raw meal is composed of low-sulfur cyanide tailings, red mud, fly ash and steel slag in a mass ratio of (9~11):(4~6):(2~4):(1~3); The amount of gypsum added is 30% ± 1% of the mass of the cement clinker.

[0006] Furthermore, the low-sulfur cyanide tailings have a moisture content ≤1% and a particle size ≤58μm; the red mud has a moisture content ≤2%; the fly ash has a moisture content ≤2%; and the steel slag, after magnetic separation to remove iron, is ground to a specific surface area ≥400m². 2 / kg; the particle size of the cementitious material is ≤45μm.

[0007] Furthermore, the alkalinity coefficient of the mixed raw material is controlled to be 0.9~1.1.

[0008] Furthermore, the cementitious material was prepared into samples with a water-cement ratio of 0.5. After curing in water at 20±1℃, the 28-day compressive strength of the cementitious material samples was not less than 42.5MPa, and there were no cracks on its surface; total cyanide was not detected in the cement clinker.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned cementitious material, comprising the following steps: Ingredient mixing: Take low-sulfur cyanide tailings, red mud, fly ash and steel slag in the mass ratio of (9~11):(4~6):(2~4):(1~3) and mix them evenly to obtain mixed raw meal; Compression molding: The mixed raw materials are compressed into raw material blocks; High-temperature roasting: The raw material blocks are roasted in an oxidizing atmosphere to obtain sulfoaluminate cement clinker; Activated grinding: Add 30% ± 1% of gypsum by weight to the sulfoaluminate cement clinker and grind them together to obtain the filling cementitious material.

[0010] Furthermore, the preparation method further includes: raw material pretreatment: drying the low-sulfur cyanide tailings to a moisture content ≤1% and crushing it to a particle size ≤58μm; drying the red mud and the fly ash to a moisture content ≤2%; and grinding the steel slag after iron removal to a specific surface area ≥400m². 2 / kg.

[0011] Furthermore, in the compression molding process, the compression molding pressure is 15MPa~20MPa.

[0012] Further, the high-temperature calcination includes: heating the raw material block to 1280℃~1320℃ in air at a heating rate of 8℃ / min~12℃ / min, holding it at that temperature for 40min~60min, and cooling it after calcination to obtain sulfoaluminate cement clinker.

[0013] Furthermore, in the activated grinding process, the particles are co-ground to a particle size ≤ 45 μm.

[0014] A third aspect of the present invention provides the application of the above-described cementitious material in mine backfilling operations.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: This invention activates the gelling activity of low-sulfur cyanide tailings through the synergistic effect of multiple solid wastes, simultaneously decomposing highly toxic cyanides in the tailings during high-temperature roasting, thus achieving the dual goals of harmless disposal and resource utilization of low-sulfur cyanide tailings. The prepared gelling material meets the compressive strength standard of 42.5 grade sulfoaluminate cement (complying with T / CCPA 36-2022 "Slag Sulfoaluminate Cement"), and can be directly used for mine backfilling operations, possessing significant environmental benefits and economic value.

[0016] This invention simultaneously achieves the goals of deep harmlessness of low-sulfur cyanide tailings (cyanide decomposition rate ≥99%), efficient utilization of multiple solid wastes (utilization rate ≥80%), and high strength of cementitious materials (≥42.5MPa). Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0018] Figure 1 The compressive strength of clinker hydration samples with gypsum addition of 0-40% provided in the embodiments of the present invention at various curing ages; Figure 2 XRD patterns of cement clinker at different calcination temperatures provided in embodiments of the present invention. Detailed Implementation

[0019] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0020] A first aspect of this invention provides a cementitious material based on low-sulfur cyanide tailings and co-processed multi-element solid waste, which is prepared by mixing and grinding sulfoaluminate cement clinker and gypsum; wherein, Sulfoaluminate cement clinker is obtained by high-temperature oxidation roasting of mixed raw meal; the mixed raw meal consists of low-sulfur cyanide tailings, red mud, fly ash and steel slag, in a mass ratio of (9~11):(4~6):(2~4):(1~3). Preferably, the mass ratio of low-sulfur cyanide tailings, red mud, fly ash and steel slag is 10:5:3:2, which can ensure the synergistic activation of cementitious activity by multiple solid wastes and meet the requirements for clinker mineral phase formation. The amount of gypsum added is 30% ± 1% of the mass of cement clinker.

[0021] Understandably, cyanide tailings with a sulfur content below 20% are generally classified as low-sulfur cyanide tailings. Current low-sulfur cyanide tailings treatment technologies have significant shortcomings: in harmless disposal technologies, acidification recovery methods consume large amounts of chemical reagents and pose a risk of HCN gas leakage; while pressure filtration and washing methods are simple to operate, some cyanide remains in the tailings, requiring further treatment. In resource utilization technologies, single-element recovery processes are complex and costly, and the utilization value of components such as silicon and aluminum in the tailings is ignored. In the field of cementitious material preparation, existing technologies have three core defects: first, the lack of a synergistic activation mechanism for multiple solid wastes makes it difficult to fully release the cementitious activity of the tailings, resulting in low product strength (mostly below 30 MPa); second, unreasonable calcination process parameters result in a cyanide decomposition rate of less than 90%, failing to meet harmless disposal requirements; and third, the lack of optimized raw material ratios leads to a utilization rate of less than 50% for multiple solid wastes, failing to fully leverage the advantages of "treating waste with waste," and some processes suffer from high energy consumption and secondary pollution.

[0022] The cementitious material based on low-sulfur cyanide tailings and co-processed solid waste provided in this embodiment of the invention simultaneously achieves the goals of deep harmlessness of low-sulfur cyanide tailings (cyanide decomposition rate ≥99%), efficient utilization of multiple solid wastes (utilization rate ≥80%), and high strength of cementitious material (≥42.5MPa).

[0023] Optionally, the low-sulfur cyanide tailings have a moisture content of ≤1% and a particle size of ≤58μm; Optionally, the moisture content of the red mud is ≤2%; Optionally, the moisture content of fly ash is ≤2%; Optionally, the steel slag is magnetically separated to remove iron and then ground to a specific surface area ≥ 400 m². 2 / kg; Optionally, the particle size of the cementitious material is ≤45μm to ensure that the hydration reaction proceeds fully.

[0024] In some embodiments, the alkalinity coefficient of the mixed raw meal is controlled to be 0.9 to 1.1; preferably, the alkalinity coefficient of the mixed raw meal is controlled to be 1.0.

[0025] The cementitious material provided in this embodiment of the invention was prepared into samples with a water-cement ratio of 0.5 and cured in water at 20±1℃. It met the performance testing standards for sulfoaluminate cement. The 28-day compressive strength of the cementitious material sample was not less than 42.5MPa, and there were no cracks on its surface. Total cyanide was not detected in the cement clinker.

[0026] A second aspect of the present invention provides a method for preparing the above-mentioned cementitious material, comprising the following steps: Ingredient mixing: Take low-sulfur cyanide tailings, red mud, fly ash and steel slag in the mass ratio of (9~11):(4~6):(2~4):(1~3) and mix them evenly to obtain mixed raw meal; Compression molding: The mixed raw materials are compressed into shapes to obtain raw material blocks; High-temperature roasting: Raw material blocks are roasted in an oxidizing atmosphere to obtain sulfoaluminate cement clinker; Activated grinding: Add 30% ± 1% of gypsum by weight to sulfoaluminate cement clinker and grind them together to obtain filling cementitious material.

[0027] like Figure 1 As shown, the compressive strength of clinker hydration samples with gypsum addition of 0-40% was investigated at various curing ages. It can be seen that the optimal gypsum addition is 30% of the cement clinker mass, which can maximize the formation of ettringite (AFt) and improve the compressive strength of cementitious materials.

[0028] In some embodiments, the preparation method of the cementitious material further includes: raw material pretreatment: drying the low-sulfur cyanide tailings to a moisture content ≤1% and crushing them to a particle size ≤58μm; drying the red mud and fly ash to a moisture content ≤2%; and grinding the steel slag after iron removal to a specific surface area ≥400m². 2 / kg.

[0029] Specifically, the above-mentioned raw material pretreatment avoids the raw material characteristics from affecting the roasting effect and gelling properties.

[0030] In some embodiments, high-temperature calcination is performed by heating raw meal blocks to 1280°C to 1320°C in air at a heating rate of 8°C / min to 12°C / min, holding at that temperature for 40 min to 60 min, and then cooling after calcination to obtain sulfoaluminate cement clinker. Preferably, high-temperature calcination is performed by heating raw meal blocks to 1300°C in air at a heating rate of 10°C / min, holding at that temperature for 40 min to 60 min, and then cooling after calcination to obtain sulfoaluminate cement clinker.

[0031] Specifically, such as Figure 2 As shown, the above roasting parameters can achieve complete decomposition of cyanide (decomposition rate ≥ 99%) and promote the formation of effective mineral phases such as C4A3_S and C4AF.

[0032] In some embodiments, during the activating grinding process, sulfoaluminate cement clinker and gypsum are ground together to a particle size ≤45μm to ensure that the hydration reaction proceeds fully.

[0033] Optionally, in the compression molding process, the compression molding pressure is 15MPa~20MPa.

[0034] A third aspect of the present invention provides the application of the above-described cementitious material in mine backfilling operations.

[0035] This invention addresses the pollution caused by the stockpiling of low-sulfur cyanide tailings and the inefficiency and high consumption of existing treatment technologies by proposing a multi-element solid waste co-utilization technology. The core idea is to use low-sulfur cyanide tailings as the main raw material, combined with red mud, fly ash, and steel slag. By optimizing the proportions and calcination process, the Fe, S, and SiO2 components in the low-sulfur cyanide tailings react with the active components in the multi-element solid waste to generate highly active sulfoaluminate cement clinker, simultaneously decomposing cyanide to achieve harmlessness. Furthermore, gypsum activation further enhances the cementitious properties, ultimately producing a cementitious material that meets the requirements for mine backfilling, achieving "waste treatment and resource recycling."

[0036] Example 1 (I) Preparation method A method for preparing a cementitious material based on low-sulfur cyanide tailings and co-processed multi-element solid waste includes the following steps: (1) Raw material pretreatment: Low-sulfur cyanide tailings (Fe mass fraction 16.37%, S mass fraction 16.50%, total cyanide content 115.67mg / L) were dried at 65℃ to constant weight (moisture content ≤1%) and crushed to particle size ≤58μm; red mud and fly ash were dried to moisture content ≤2%; steel slag was magnetically separated to remove iron and then ground to a specific surface area ≥400m². 2 / kg.

[0037] (2) Ingredient mixing: Weigh 40g of low-sulfur cyanide tailings, 20g of red mud, 12g of fly ash and 8g of steel slag according to the mass ratio of 10:5:3:2, add them to the mixer and stir for 20min to obtain raw material; the alkalinity coefficient of the raw material is controlled to be 1.0.

[0038] (3) Pressing and molding: Add the raw material to the tablet press and press it under a pressure of 15MPa~20MPa to form a cylindrical raw material block of Φ15mm×(20~30) mm, and let it stand naturally for 2 hours.

[0039] (4) High-temperature calcination: The raw material blocks are placed in an electric resistance furnace and heated to 1300℃ at 10℃ / min. The temperature is maintained for 40min. Air is introduced during the calcination process as an oxidizing atmosphere. After the calcination is completed, the raw material blocks are quickly removed and air-cooled to room temperature to obtain sulfoaluminate cement clinker.

[0040] (5) Activation grinding: Add 30% by mass of CaSO4 to the cement clinker 2H2O was used as an activator and added to a ball mill to grind to ≤45μm. After being mixed evenly, the filling cementitious material was obtained.

[0041] (ii) Performance testing Cementitious material samples of 2×2×2cm were prepared with a water-cement ratio of 0.5 and cured in water at 20±1℃. The compressive strength was measured at 1d, 3d, 7d and 28d, and the total cyanide content in the clinker was detected simultaneously. See Table 1 for details.

[0042] Example 2 (I) Preparation method A method for preparing a cementitious material based on low-sulfur cyanide tailings and co-processed multi-element solid waste includes the following steps: (1) Raw material pretreatment: Low sulfur cyanide tailings (Fe mass fraction 16.37%, S mass fraction 16.50%, total cyanide content 115.67mg / L) were dried at 65℃ to constant weight (moisture content ≤1%) and crushed to particle size ≤58μm; red mud and fly ash were dried to moisture content ≤2%; steel slag was magnetically separated to remove iron and then ground to specific surface area ≥400m² / kg.

[0043] (2) Ingredient mixing: Weigh 40g of low-sulfur cyanide tailings, 20g of red mud, 12g of fly ash and 8g of steel slag according to the mass ratio of 10:5:3:2, add them to the mixer and stir for 20min to obtain raw material; the alkalinity coefficient of the raw material is controlled to be 1.0.

[0044] (3) Pressing and molding: Add the raw material to the tablet press and press it under a pressure of 15MPa~20MPa to form a cylindrical raw material block of Φ15mm×(20~30) mm, and let it stand naturally for 2 hours.

[0045] (4) High-temperature calcination: The raw material blocks are placed in an electric resistance furnace and heated to 1300℃ at 10℃ / min. The temperature is maintained for 60min. Air is introduced during the calcination process as an oxidizing atmosphere. After the calcination is completed, the raw material blocks are quickly removed and air-cooled to room temperature to obtain sulfoaluminate cement clinker.

[0046] (5) Activation grinding: Add 30% by mass of CaSO4 to the cement clinker 2H2O was used as an activator and added to a ball mill to grind to ≤45μm. After being mixed evenly, the filling cementitious material was obtained.

[0047] (ii) Performance testing Cementitious material samples of 2×2×2cm were prepared with a water-cement ratio of 0.5 and cured in water at 20±1℃. The compressive strength was measured at 1d, 3d, 7d and 28d, and the total cyanide content in the clinker was detected simultaneously. See Table 1 for details.

[0048] Example 3 (I) Preparation method A method for preparing a cementitious material based on low-sulfur cyanide tailings and co-processed multi-element solid waste includes the following steps: (1) Raw material pretreatment: Low sulfur cyanide tailings (Fe mass fraction 16.37%, S mass fraction 16.50%, total cyanide content 115.67mg / L) were dried at 65℃ to constant weight (moisture content ≤1%) and crushed to particle size ≤58μm; red mud and fly ash were dried to moisture content ≤2%; steel slag was magnetically separated to remove iron and then ground to specific surface area ≥400m² / kg.

[0049] (2) Ingredient mixing: Weigh 44g of low-sulfur cyanide tailings, 16g of red mud, 12g of fly ash and 8g of steel slag according to the mass ratio of 11:4:3:2, add them to the mixer and stir for 20 minutes to obtain raw material; the alkalinity coefficient of the raw material is controlled to be 1.0.

[0050] (3) Pressing and molding: Add the raw material to the tablet press and press it under a pressure of 15MPa~20MPa to form a cylindrical raw material block of Φ15mm×(20~30) mm, and let it stand naturally for 2 hours.

[0051] (4) High-temperature calcination: The raw material blocks are placed in an electric resistance furnace and heated to 1300℃ at 10℃ / min. The temperature is maintained for 50min. Air is introduced during the calcination process as an oxidizing atmosphere. After the calcination is completed, the raw material blocks are quickly removed and air-cooled to room temperature to obtain sulfoaluminate cement clinker.

[0052] (5) Activation grinding: Add 30% by mass of CaSO4 to the cement clinker 2H2O was used as an activator and added to a ball mill to grind to ≤45μm. After being mixed evenly, the filling cementitious material was obtained.

[0053] (ii) Performance testing Cementitious material samples of 2×2×2cm were prepared with a water-cement ratio of 0.5 and cured in water at 20±1℃. The compressive strength was measured at 1d, 3d, 7d and 28d, and the total cyanide content in the clinker was detected simultaneously. See Table 1 for details.

[0054] Example 4 (I) Preparation method A method for preparing a cementitious material based on low-sulfur cyanide tailings and co-processed multi-element solid waste includes the following steps: (1) Raw material pretreatment: Low sulfur cyanide tailings (Fe mass fraction 16.37%, S mass fraction 16.50%, total cyanide content 115.67mg / L) were dried at 65℃ to constant weight (moisture content ≤1%) and crushed to particle size ≤58μm; red mud and fly ash were dried to moisture content ≤2%; steel slag was magnetically separated to remove iron and then ground to specific surface area ≥400m² / kg.

[0055] (2) Ingredient mixing: Weigh 40g of low-sulfur cyanide tailings, 20g of red mud, 12g of fly ash and 8g of steel slag according to the mass ratio of 10:5:3:2, add them to the mixer and stir for 20min to obtain raw material; the alkalinity coefficient of the raw material is controlled to be 1.0.

[0056] (3) Pressing and molding: Add the raw material to the tablet press and press it under a pressure of 15MPa~20MPa to form a cylindrical raw material block of Φ15mm×(20~30) mm, and let it stand naturally for 2 hours.

[0057] (4) High-temperature calcination: The raw material blocks are placed in an electric resistance furnace and heated to 1300℃ at 10℃ / min. The temperature is maintained for 60min. Air is introduced during the calcination process as an oxidizing atmosphere. After the calcination is completed, the raw material blocks are quickly removed and air-cooled to room temperature to obtain sulfoaluminate cement clinker.

[0058] (5) Activation grinding: Add 30% by mass of CaSO4 to the cement clinker 2H2O was used as an activator and added to a ball mill to grind to ≤45μm. After being mixed evenly, the filling cementitious material was obtained.

[0059] (ii) Performance testing Cementitious material samples of 2×2×2cm were prepared with a water-cement ratio of 0.5 and cured in water at 20±1℃. The compressive strength was measured at 1d, 3d, 7d and 28d, and the total cyanide content in the clinker was detected simultaneously. See Table 1 for details.

[0060] Comparative Example 1 (I) Preparation method A method for preparing a cementitious material based on low-sulfur cyanide tailings includes the following steps: (1) Raw material pretreatment: Low sulfur cyanide tailings (Fe mass fraction 16.37%, S mass fraction 16.50%, total cyanide content 115.67mg / L) are dried at 65℃ to constant weight (moisture content ≤1%) and crushed to particle size ≤58μm; limestone is dried and crushed to particle size ≤58μm; alumina is reserved.

[0061] (2) Ingredient mixing: Weigh 40g of low-sulfur cyanide tailings, 24g of limestone and 16g of alumina according to the mass ratio of 5:3:2, add them to the mixer and stir for 20 minutes to obtain raw material.

[0062] (3) Pressing and molding: Add the raw material to the tablet press and press it under a pressure of 15MPa~20MPa to form a cylindrical raw material block of Φ15mm×(20~30) mm, and let it stand naturally for 2 hours.

[0063] (4) High-temperature roasting: Place the raw material blocks into an electric resistance furnace and heat them to 1300℃ at 10℃ / min. Keep them at that temperature for 40min. During the roasting process, air is introduced as an oxidizing atmosphere. After the roasting is completed, the raw material blocks are quickly removed and air-cooled to room temperature to obtain the cooked material.

[0064] (5) Activation grinding: Add 30% by mass of CaSO4 to the clinker. 2H2O was used as an activator and added to a ball mill to grind to ≤45μm. After being mixed evenly, a cementitious material was obtained.

[0065] (ii) Performance testing Cementitious material samples of 2×2×2cm were prepared with a water-cement ratio of 0.5 and cured in water at 20±1℃. The compressive strength was measured at 1d, 3d, 7d and 28d, and the total cyanide content in the clinker was detected simultaneously. See Table 1 for details.

[0066] Comparative Example 2 (I) Preparation Method A method for preparing a cementitious material based on low-sulfur cyanide tailings and co-processed multi-element solid waste includes the following steps: (1) Raw material pretreatment: Low sulfur cyanide tailings (Fe mass fraction 16.37%, S mass fraction 16.50%, total cyanide content 115.67mg / L) were dried at 65℃ to constant weight (moisture content ≤1%) and crushed to particle size ≤58μm; red mud and fly ash were dried to moisture content ≤2%; steel slag was magnetically separated to remove iron and then ground to specific surface area ≥400m² / kg.

[0067] (2) Ingredient mixing: Weigh 40g of low-sulfur cyanide tailings, 20g of red mud, 12g of fly ash and 8g of steel slag according to the mass ratio of 10:5:3:2, add them to the mixer and stir for 20min to obtain raw material; the alkalinity coefficient of the raw material is controlled to be 1.0.

[0068] (3) Pressing and molding: Add the raw material to the tablet press and press it under a pressure of 15MPa~20MPa to form a cylindrical raw material block of Φ15mm×(20~30) mm, and let it stand naturally for 2 hours.

[0069] (4) High-temperature calcination: The raw material blocks are placed in an electric resistance furnace and heated to 1250°C at 10°C / min. The temperature is maintained for 40 min. Air is introduced during the calcination process as an oxidizing atmosphere. After the calcination is completed, the raw material blocks are quickly removed and air-cooled to room temperature to obtain sulfoaluminate cement clinker.

[0070] (5) Activation grinding: Add 30% by mass of CaSO4 to the cement clinker 2H2O was used as an activator and added to a ball mill to grind to ≤45μm. After being mixed evenly, the filling cementitious material was obtained.

[0071] (ii) Performance testing Cementitious material samples of 2×2×2cm were prepared with a water-cement ratio of 0.5 and cured in water at 20±1℃. The compressive strength was measured at 1d, 3d, 7d and 28d, and the total cyanide content in the clinker was detected simultaneously. See Table 1 for details.

[0072] Comparative Example 3 (I) Preparation Method A method for preparing a cementitious material based on low-sulfur cyanide tailings and co-processed multi-element solid waste includes the following steps: (1) Raw material pretreatment: Low sulfur cyanide tailings (Fe mass fraction 16.37%, S mass fraction 16.50%, total cyanide content 115.67mg / L) were dried at 65℃ to constant weight (moisture content ≤1%) and crushed to particle size ≤58μm; red mud and fly ash were dried to moisture content ≤2%; steel slag was magnetically separated to remove iron and then ground to specific surface area ≥400m² / kg.

[0073] (2) Ingredient mixing: Weigh 40g of low-sulfur cyanide tailings, 20g of red mud, 12g of fly ash and 8g of steel slag according to the mass ratio of 10:5:3:2, add them to the mixer and stir for 20min to obtain raw material; the alkalinity coefficient of the raw material is controlled to be 1.0.

[0074] (3) Pressing and molding: Add the raw material to the tablet press and press it under a pressure of 15MPa~20MPa to form a cylindrical raw material block of Φ15mm×(20~30) mm, and let it stand naturally for 2 hours.

[0075] (4) High-temperature calcination: The raw material blocks are placed in an electric resistance furnace and heated to 1300℃ at 10℃ / min. The temperature is maintained for 40min. Air is introduced during the calcination process as an oxidizing atmosphere. After the calcination is completed, the raw material blocks are quickly removed and air-cooled to room temperature to obtain sulfoaluminate cement clinker.

[0076] (5) Activation grinding: Add 40% by mass of CaSO4 to the cement clinker 2H2O was used as an activator and added to a ball mill to grind to ≤45μm. After being mixed evenly, the filling cementitious material was obtained.

[0077] (ii) Performance testing Cementitious material samples of 2×2×2cm were prepared with a water-cement ratio of 0.5 and cured in water at 20±1℃. The compressive strength was measured at 1d, 3d, 7d and 28d, and the total cyanide content in the clinker was detected simultaneously. See Table 1 for details.

[0078] Table 1. Performance test results of the filling cementitious materials obtained in Examples 1-4 and Comparative Examples 1-3.

[0079] The difference between Comparative Example 1 and Example 1 is that the raw materials are 40g of low-sulfur cyanide tailings, 24g of limestone, and 16g of alumina. As shown in Table 1, the 28-day compressive strength of Comparative Example 1 is 38.5MPa, which does not meet the standard for 42.5# cement; the total cyanide content in the clinker of Comparative Example 1 is 8.91mg / L, with a decomposition rate of 92.3%, which does not meet the requirements for harmlessness.

[0080] The difference between Comparative Example 2 and Example 1 is that the high-temperature calcination temperature was 1250℃. As can be seen from Table 1, the 28-day compressive strength of Comparative Example 2 was 42.1 MPa, which did not meet the standard for 42.5# cement; the total cyanide content of the clinker in Comparative Example 2 was 8.7 mg / L, and the decomposition rate was 92.5%, which did not meet the requirements for harmlessness.

[0081] The difference between Comparative Example 3 and Example 1 is that 40% by mass of CaSO4 was added to the cement clinker during the activating grinding process. 2H2O was used as an activator. As can be seen from Table 1, the 28-day compressive strength of Comparative Example 3 was 40.3 MPa, which did not meet the standard of 42.5# cement; the total cyanide in the clinker of Comparative Example 3 was not detected, and the decomposition rate was 99.9%; the sample surface cracked, and the cracks were caused by excessive gypsum leading to coarse AFt grains.

[0082] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A cementitious material based on low-sulfur cyanide tailings and co-processed multi-element solid waste, characterized in that, It is made by mixing and grinding sulfoaluminate cement clinker and gypsum; among which, The sulfoaluminate cement clinker is obtained by high-temperature oxidation roasting of mixed raw meal; the mixed raw meal is composed of low-sulfur cyanide tailings, red mud, fly ash and steel slag in a mass ratio of (9~11):(4~6):(2~4):(1~3); The amount of gypsum added is 30% ± 1% of the mass of the cement clinker.

2. The cementitious material according to claim 1, characterized in that, The low-sulfur cyanide tailings have a moisture content ≤1% and a particle size ≤58μm; the red mud has a moisture content ≤2%; the fly ash has a moisture content ≤2%; and the steel slag, after magnetic separation to remove iron, is ground to a specific surface area ≥400m². 2 / kg; the particle size of the cementitious material is ≤45μm.

3. The cementitious material according to claim 1, characterized in that, In the mixed raw materials, the alkalinity coefficient is controlled to be 0.9~1.

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4. The cementitious material according to any one of claims 1 to 3, characterized in that, The cementitious material was prepared into samples with a water-cement ratio of 0.

5. After curing in water at 20±1℃, the 28-day compressive strength of the cementitious material samples was not less than 42.5MPa, and there were no cracks on its surface. Total cyanide was not detected in the cement clinker.

5. A method for preparing the cementitious material according to any one of claims 1 to 4, characterized in that, Includes the following steps: Ingredient mixing: Take low-sulfur cyanide tailings, red mud, fly ash and steel slag in the mass ratio of (9~11):(4~6):(2~4):(1~3) and mix them evenly to obtain mixed raw meal; Compression molding: The mixed raw materials are compressed into raw material blocks; High-temperature roasting: The raw material blocks are roasted in an oxidizing atmosphere to obtain sulfoaluminate cement clinker; Activated grinding: Add 30% ± 1% of gypsum by weight to the sulfoaluminate cement clinker and grind them together to obtain the filling cementitious material.

6. The preparation method according to claim 5, characterized in that, The preparation method further includes: raw material pretreatment: drying the low-sulfur cyanide tailings to a moisture content ≤1% and crushing it to a particle size ≤58μm; drying the red mud and fly ash to a moisture content ≤2%; and grinding the steel slag after iron removal to a specific surface area ≥400m². 2 / kg.

7. The preparation method according to claim 5, characterized in that, In the compression molding process, the compression molding pressure is 15MPa~20MPa.

8. The preparation method according to claim 5, characterized in that, The high-temperature roasting includes: The raw material blocks are heated to 1280℃~1320℃ in air at a heating rate of 8℃ / min~12℃ / min and held at that temperature for 40min~60min. After calcination, the blocks are cooled to obtain sulfoaluminate cement clinker.

9. The preparation method according to claim 5, characterized in that, In the activated grinding process, the particles are ground together until the particle size is ≤45μm.

10. The application of any one of the cementitious materials according to claims 1 to 4 in mine backfilling operations.

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